Carbs and Protein: Do We Need Both After a Workout?

You've probably heard people talk about the ideal ratio of carbs to protein post workout. It is generally believed you might need a 2:1 or 3:1 ratio of carbs to protein as soon after working out as possible, or maybe even higher. You might have also heard the carbs need to have a high glycemic index, meaning they are easy to digest and have the greatest ability to deliver protein to muscle.

However, some people believe these notions are simply supplement company hype combined with misinterpretations of existing studies. In a review published this month in the Journal of the International Society of Sports Nutrition, researchers examined the existing literature on this topic. The researchers focused on the importance of carbs ingested with protein after a workout and also asked whether the carbs need to have a high glycemic index in order to be most effective as a recovery aid.

The first and foremost reason to ingest carbs post workout is to replenish glycogen stores. Glycogen is the chemical form of carbohydrates that is stored in the muscles. When you do any kind of exercise that requires you to burn your glycogen stores, it’s important you replace the gylcogen that was lost.

However, that’s not really the issue with a post-workout ratio of carbs to protein. In some workouts, you may burn a few grams glycogen for fuel, and in others you may nearly exhaust the glycogen in your skeletal muscle. You also need protein after exercise to repair and build muscle tissue. Getting enough protein after workouts will help stimulate protein synthesis, which is the creation of new muscle.

The main purpose of a ratio of carbs to protein is to further stimulate protein synthesis. Protein synthesis would theoretically occur as a result of an increase in insulin, which is where the high glycemic value comes in. When a carbohydrate has a high glycemic index, it enters the bloodstream quickly and usually stimulates insulin quickly. Insulin is an anabolic hormone, meaning it supports the creation of new muscle, generally by improving the uptake of protein – and, incidentally, the carbs that come in with the protein.

As it turns out, this extra insulin boost from high-glycemic carbs is probably not necessary. While insulin is needed for protein synthesis, it seems that the low amounts stimulated by protein alone are sufficient for the creation of new muscle. In fact, the researchers found post-exercise insulin levels that were thirty times higher than resting insulin levels did not seem to affect protein synthesis.

Further, protein degradation caused by exercise is sometimes cited as another reason we need high insulin-promoting carbs after exercise. However, once again, the amount of insulin stimulated by protein alone is sufficient to prevent protein breakdown after exercise.

Carbohydrates may be useful for recovery in some scenarios, such as when you need to recover quickly between workouts. However, when it comes to repairing or building muscle through the stimulation of protein synthesis, the researchers said more research is warranted. At present, there is no evidence to support the claim that post-workout carbs in any ratio are needed for protein synthesis. Protein seems to be enough on its own.